package practice;


    abstract class Shape {
        double Aera=10;
        abstract double getAera();
    }
    class Circle extends Shape{
        @Override
        double getAera() {
            System.out.println("圆形的面积为"+this.Aera);
            return this.Aera;
        }
    }
    class Square extends Shape{
        @Override
        double getAera() {
            System.out.println("正方形的面积为"+this.Aera);
            return this.Aera;
        }
    }
    class Rectangle extends Shape{
        @Override
        double getAera() {
            System.out.println("长方形的面积为"+this.Aera);
            return this.Aera;
        }
    }
     class Example {
        public static void main(String args[]){
            Circle a=new Circle();
            Square b=new Square();
            Rectangle c=new Rectangle();
            a.getAera();
            b.getAera();
            c.getAera();
        }
    }

